Kenneth Michael Guitars est.1978
Trimming  the Top or Back Edges -- Flapper wheel method
I found that an abrasive 80-grit flapper wheel (Sears and others) works well for
trimming the tops or back flush to the rim. This procedure is less aggressive than a
router with a flush cutting bit. However care must be taken to avoid tear out. The
areas indicated by the blue tape are the most vulnerable. Sometimes the top or
back is not in perfect contact with the rim and kerfing. Consequently, the
combination of end grain and a poor glue joint can cause a problem.  
The rim must be secure and stable. Also cover the top or back with a piece of
cardboard, there is a chance that you will bounce off the edge and this could
damage the top or back.
Trim the precautionary areas first, tilt the
drill and flapper wheel in such a way that it is
sanding/trimming in a slightly downward
angle to the face of the top or back.
I think you will find that this process is much
less intimidating than whacking at your
newborn guitar body with a high-powered
router. You may need to do a little hand
sanding; this is necessary even with the
router procedure. Work slowly to prevent
damage to the rim. Still this method is much
quicker and more accurate than hand tools.